Rock and Taker have never even booked to have a meaningful feud between each other. The only high profile 1-1 match they ever had was Rock v Taker at King of the Ring 99 and that was just a filler match in between Owen dying on the previous PPV and Austin winning the belt the day after King of the Ring.

I wonder why that didn't feel special or memorable?

There's a reason why they were never booked to have a meaningful feud between each other. Because they sucked together.

Their characters don't mix. It's like seeing Elvis vs. Boris Karloff. Their characters are too far from one another in the universe to create a meaningful feud between them. Even now, if they were to "feud" (i.e., cut a dozen promos with each other, since that's what it would be for Wrestlemania), it would feel awkward and forced. I can think of a few avenues they could take with it--"Team Bring It" vs. "The Creatures of the Night"? Nevertheless, it doesn't excite me any, at all. Let's also be brutally honest: Undertaker was the least among the triumvirate of Taker-Triple H-Michaels this past Road to Wrestlemania when it came to promo work. He received "WHAT?" chants and was even getting boos here and there for some shaky mic work. Seeing him paired up with Rock would probably render the problem altogether more pressing. At least with Lesnar, Heyman can do the heavy lifting and sell the storyline without necessitating too much mic effort from either Taker or Lesnar.

The best thing that ever took place between Rock and Taker was Rock kicking Taker back down with the "Rock Stomp" after Taker "sat up" mid-People's Elbow on a random Raw in the fall of 1998. The rest of the match? Nope. Their match at Survivor Series later that fall? Boring Attitude Era "brawl," nothing offensive but unmemorable in the extreme. Their match at King of the Ring 1999 is actually atrocious, a nearly 20-minute snoozefest. Austin winning the title back the next night had nothing to do with it. By that point that night, I had repressed the match between Taker and Rock the night before because it was just so poor.

When I think of Rock and Undertaker, I think of Rock's December 2000 promo in which he mocked Taker's eye-rolling shtick (though Taker was the "American Badass" character at the time). Again, it was hysterical in large part because of how massive the gulf between those characters truly is.

To reiterate a point I made in a thread regarding Shawn Michaels having one last match--and it quickly was dominated by talk of Rock and HBK working together one day--"...Rock wrestling a guy who will be pushing 50 when they could ever conceivably lock it up in the middle of the ring in 2012, with Rock standing in as the Hogan figure from 2002 that he wrestled once upon a time as the young megastar, is just taking a backward step for WWE. And I'm sure Rock himself knows that. Since returning, Rock has been and continues to be working with Cena and Punk and Miz, not with guys who he either worked with a decade ago and don't need any further interaction with him or even legends like Michaels who he somehow missed out on ever working with. He's a lot cagier and wiser than he's given credit for, seems to me."

I think Rock's own fans aren't giving their own hero enough credit for having such a smart, well-rounded view of the business.

This isn't ruling out Lesnar/Rock as a possibility one day as a simple major attraction to boost a Summerslam or a Survivor Series one day, but at least as far as Wrestlemania XXIX is concerned, it seems like both men have entirely different trajectories. They've made it clear that as far as Cena and Rock are concerned, they have unfinished business with one another (their dialogue at Raw 1,000 saying as much), and Rock's locked in to wrestle Punk, almost surely at The Royal Rumble. Rock freeing himself up for Lesnar would require quite a few tricks in booking at this point. Meanwhile, Lesnar is here solely for big money and to work with the biggest possible names, and after Cena and Triple H, and with Rock busy with today's bigger stars, Undertaker would be next in line for Lesnar.

They had a singles match at No Way Out 2002 where Rock won. Rock vs Taker for some reason does not sound right. Rock vs Punk, vs Lesnar and even vs Cena again sound good but this one just doesn't for me at least.

Rock and Taker had a few good to great matches 98 to 99. RAW in October 98 IIRC was good, KOTR 99 was great, when Orton and HHH used the early finisher concept in their WM25 match, the first thing that came to my mind was Rock/Taker at KOTR. NWO 2002 was decent and they had more TV matches in 2000. At SVS 98 there's a funny spot where Rock is giving Taker a DDT and then mocking his Deadman sit up, then mocking Bearer for being as he said "a big fat piece of shit!" lol. Good times. Anyway, they never booked for a program together because it was never the right time, always a problem between injuries, babface/heel dynamics or bigger matches. They can definitely work a WM main event, the story is already there from the story of this year's Rock/Cena match with Rock saying that he needs to beat Cena to be the GOAT.

But with that said, Rock/Brock is more attractive than Rock/Taker IMO and that's what it should be, along with Taker/Cena as the co-main event. In the past Vince had a philosophy that at WM, he wants only new and fresh matches, preferably first time ever. Then the Rock/Austin series came out, broke records and worked so well that it meant to happen again. But other than that, I hope Vince goes to what he said in the past and don't give us the same matches at WM every year, especially when both results are the most predictable of all time.